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Ömsesidighet som skapande av inflytande i EU? : En idéanalytisk fallstudie om småstaters inflytande över beslutsprocessen i GUSPNilsson, Simone January 2017 (has links)
This thesis studies the impact of small states in the Common Foreign and Security Policy (CFSP) in EU. The organisation of EU contains an interdependent power relationship between all countries. The aim of this study is to examine how this interdependence affect the influence of small states. Two theoretical framework are used. The first by Robert Keohane och Joseph Nye that developed the theoretical definition of interdependence, while the second one by Søren Christensen and his definition of direct and indirect power. The analytical model contains four hypothesis concerning asymmetrical and vulnerable interdependence, as well as direct- and indirect power. Through a case study of Sweden and Finland the conclusion is that small states have influence in CFSP, but it is limited due to bigger states with much more resources and the geographical position of the countries that creats asymmetrical interdependence. However, Sweden and Finland have influence in the decision-making in CFSP through vulnerable interdependence because of their many international defence cooperations with different organizations that strengthen their national position in the international political system. Also, the formal process of decision-making in CFSP enable direct and indirect power of small states. Therefore, the final conclusion is that small states have influence in CFSP even though is its limited in some aspects.
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Direct Power Control of a Doubly Fed Induction Generator in Wind Power SystemsSam, Mahmodicherati 04 October 2016 (has links)
No description available.
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Steady State And Dynamic Analysis And Optimization Of Single-stage Power Factor Correction ConvertersRustom, Khalid 01 January 2007 (has links)
With the increased interest in applying Power Factor Correction (PFC) to off-line AC-DC converters, the field of integrated, single-stage PFC converter development has attracted wide attention. Considering the tens of millions of low-to-medium power supplies manufactured each year for today's rechargeable equipment, the expected reduction in cost by utilizing advanced technologies is significant. To date, only a few single-stage topologies have made it to the market due to the inherit limitations in this structure. The high voltage and current stresses on the components led to reduced efficiency and an increased failure rate. In addition, the component prices tend to increase with increased electrical and thermal requirements, jeopardizing the overarching goal of price reduction. The absence of dedicated control circuitry for each stage complicates the power balance in these converters, often resulting in an oversized bus capacitance. These factors have impeded widespread acceptance of these new techniques by manufacturers, and as such single stage PFC has remained largely a drawing board concept. This dissertation will present an in-depth study of innovative solutions that address these problems directly, rather than proposing more topologies with the same type of issues. The direct energy transfer concept is analyzed and presented as a promising solution for the majority of the single-stage PFC converter limitations. Three topologies are presented and analyzed based on this innovative structure. To complete the picture, the dynamics of a variety of single-stage converters can be analyzed using a proposed switched transformer model.
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Controle direto de potência deadbeat para o gerador de indução com dupla alimentação operando durante afundamento de tensão aplicado à geração eólicaFranco, Rodrigo January 2014 (has links)
Orientador: Prof. Dr. Alfeu Joãozinho Sguarezi Filho / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2014. / A energia eólica tem seu interesse aumentado nos últimos anos como uma das
mais importantes fontes de energia renováveis devido a sua característica
ecologicamente correta. Um dos componentes principais do sistema de geração eólica
é o aerogerador, que deve ser capaz de operar com velocidade variável do vento e
deve estar conectado à rede elétrica mesmo com a presença de distúrbios elétricos,
como afundamento de tensão.
Este trabalho apresenta uma proposta de controlador direto de potência do tipo
deadbeat para o Gerador de Indução com Dupla Alimentação (GIDA), onde tem-se
seu estator conectado diretamente à rede elétrica e o seu rotor, conectado à rede
elétrica com o emprego de um conversor bidirecional. O controlador proposto é
projetado a partir do modelo matemático dinâmico discreto do GIDA para trabalhar
durante a ocorrência de afundamentos de tensão sem o emprego de crowbar e sem
danificar a máquina de indução.
O GIDA e o controlador direto de potência deadbeat foram simulados com o
emprego do pagote Simulink® do Matlab® e os resultados desta simulação são
apresentados nesta dissertação, incluindo a operação do GIDA durante afundamento
de tensão trifásico equilibrado.
Para comprovar a capacidade de operação durante afundamento de tensão,
foram realizados testes em bancada com o controlador direto de potência proposto e
os resultados experimentais apresentados validam a correta operação do controlador
direto de potência deadbeat na condição de falha da rede. / Wind energy is gaining interest in the last years as one of the most important
renewable sources of energy due to its ecofriendly nature. One of the main
components of the wind energy system is the wind generator, which must be able to
work with variable wind speed and have to be connected directly to the grid even during
faults, like symmetrical sag.
This work presents a proposal of a direct power control deadbeat for Doubly-Fed
Induction Generator (DFIG), where its stator is connected directly to the grid and its
rotor is connected to the grid trough a bidirectional converter. The proposed controller
is designed using the mathematical discretized dynamic model of DFIG, with the goal
to withstand its operation during sag with no crowbar and avoiding damage to the
induction machine.
The DFIG and the direct power controller deadbeat were simulated using the suite
Simulink® from Matlab® and the results are presented in this work, including the DFIG
operation during symmetrical sag.
For assuring the performance of the controller during sag, practical results with the
proposed direct power controlled were performed using a test bench and the final
results validate the correct design of the proposed deadbeat direct power controller.
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Controle preditivo generalizado com horizonte deslizante e controle direto de potência deadbeat aplicados em sistemas eólicos baseados no gerador de indução de rotor bobinadoChaves, Juan Sebastián Solís January 2017 (has links)
Orientador: Prof. Dr. Alfeu J. Sguarezi Filho / Tese (doutorado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2017. / Nesta pesquisa são propostos dois novos algoritmos de controle, operando a velocidade
variável e robustos às variações nos parâmetros para um sistema eólico baseado no gerador
de indução duplamente alimentado, cuja aplicação é realizada em condições normais de
operação. Os controladores propostos são nomeados de Controle Direto de Potência (CDP)
Deadbeat e do Controle Preditivo Generalizado com Horizonte Deslizante (CPG¿hd). O
primeiro possui duas malhas de controle: uma para o desacoplamento do fluxo do estator
e o controle das potências e a outra para o controle da corrente, essa malha é chamada
de Deadbeat. O CDP calcula o vetor de tensão fornecido ao rotor a fim de garantir que
a potência ativa e reativa atinjam seus valores de referência desejados. A dependência
do algoritmo a parâmetros que tenham que ser sintonizados por meio de procedimentos
heurísticos é nula quando é comparado com o controle Proporcional¿Integral ou Controle
PI, sendo preciso somente calcular o coeficiente Gc. O segundo controlador, calcula os
preditores para a corrente do rotor usando um horizonte de predição definido e assim obter
as novas tensões do rotor que devem ser injetadas no sistema para controlar as potências
ativa e reativa do estator com base nas equações do gerador. O CPG¿hd precisa de um
parâmetro para sua sintonização chamado fator de peso do controlador, esse parâmetro faz
parte da função de custo quadrática que deve ser minimizada, para obter um valor ótimo
das tensões do rotor. Testes são feitos usando Matlab¿Simulink para os dois controladores
operando sob condições normais de operação, ou seja: teste a velocidade fixa e teste a
velocidade variável do rotor. Os mesmos testes são repetidos por meio de um protótipo de
escala pequena disponível no LEPS . A dependência dos dois algoritmos às variações dos
parâmetros foi também investigada, assim como a influência dos erros na estimativa desses
parâmetros, obtendo-se um desempenho superior do controlador preditivo generalizado
CPG¿hd sobre o CDP Deadbeat. / In this research two new control algorithms for a wind power system based on the Double
Fed Induction Generator (DFIG) are proposed. The wind energy system is operating under
normal conditions i.e. fixed rotor speed, variable rotor speed and under variations in DFIG
parameters. The proposed controllers are named Direct Power Control (DPC) Deadbeat
and Long¿range Generalized Predictive Control (GPC¿dq). The DPC calculates the sup-
plied voltage vector to the rotor to ensure that the active and reactive power reaches their
desired reference values. The algorithm dependence on parameters that have to be tuned
by means of heuristic procedures is zero when its compared with the Proportional¿Integral
(PI) Control, being necessary only estimate the Gc coeficient. The second controller evalu-
ates the DFIG predictive rotor currents, using a defined long-range prediction horizon and
thus obtain the new rotor voltages that have to be injected to controlling the active and
reactive stator powers. The GPC¿dq needs a parameter for been tuned, this is called as a
weighting factor and is a part of the quadratic cost function that has to be minimized, to
obtain an optimal value of the rotor voltages. Tests are done using Matlab¿Simulink for
the two controllers operating under normal operating conditions, ie: a fixed speed test and
a variable rotor speed test. The same tests are repeated using a small scale prototype avai-
lable in the LEPS. The dependence of the two algorithms on the parameter variations was
also investigated, as well as the influence of the errors in the estimation of these parame-
ters, obtaining a superior performance for the long¿range generalized predictive controller
over the other one.
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Algorithmes de conception de lois de commande prédictives pour les systèmes de production d’énergie / Control design algorithms for Model-Based Predictive Power Control. Application for Wind EnergyNgo, Van Quang Binh 22 June 2017 (has links)
Cette thèse vise à élaborer de nouvelles stratégies de commande basées sur la commande prédictive pour le système de génération d’énergie éolienne. La topologie des systèmes de production éolienne basées sur le Générateur Asynchrone à Double Alimentation (GADA) qui convient à des plateformes de génération dans la gamme de puissance de 1.5 à 6 MW est abordée. Du point de vue technologique, le convertisseur à trois niveaux et clampé par le neutre (3L-NPC) est considéré comme une bonne solution pour une puissance élevée en raison de ses avantages: capacité à réduire la distorsion harmonique de la tension de sortie et du courant, et augmentation de la capacité du convertisseur grâce à une tension réduite appliquée à chaque semi-conducteur de puissance. Une description détaillée de la commande prédictive à ensemble de commande fini (FCS-MPC) avec un horizon de prédiction de deux pas est présentée pour deux boucles de régulation: celle liée au convertisseur connecté au réseau et celle du convertisseur connecté au GADA. Le principe de la commande repose sur l’utilisation d’un modèle de prédiction permettant de prédire le comportement du système pour chaque état de commutation du convertisseur. La minimisation d’une fonction de coût appropriée prédéfinie permet d’obtenir la commutation optimale à appliquer au convertisseur. La thèse étudie premièrement les problèmes liées à la compensation du temps de calcul de la commande et au choix et aux pondérations de la fonction de coût. Ensuite, le problème de stabilité de la commande FCS-MPC est abordé en considérant une fonction de Lyapunov dans la minimisation de la fonction de coût. Finalement, une étude sur la compensation des effets des temps morts du convertisseur est présentée. / This thesis aims to elaborate new control strategies based on Model Predictive control for wind energy generation system. We addressed the topology of doubly fed induction generator (DFIG) based wind generation systems which is suitable for generation platform power in the range in 1.5-6 MW. Furthermore, from the technological point of view, the three-level neutral-point clamped (3L-NPC) inverter configuration is considered a good solution for high power due to its advantages: capability to reduce the harmonic distortion of the output voltage and current, and increase the capacity of the converter thanks to a decreased voltage applied to each power semiconductor.In this thesis, we presented a detailed description of finite control set model predictive control (FCS-MPC) with two step horizon for two control schemes: grid and DFIG connected 3L-NPC inverter. The principle of the proposed control scheme is to use system model to predict the behaviour of the system for every switching states of the inverter. Then, the optimal switching state that minimizes an appropriate predefined cost function is selected and applied directly to the inverter.The study of issues such as delay compensation, computational burden and selection of weighting factor are also addressed in this thesis. In addition, the stability problem of FCS-MPC is solved by considering the control Lyapunov function in the design procedure. The latter study is focused on the compensation of dead-time effect of power converter.
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